System and method for parallel solution extraction of one or more metal values from metal-bearing materials

ABSTRACT

The present disclosure relates to a process and system for recovery of one or more metal values using solution extraction techniques and to a system for metal value recovery. In an exemplary embodiment, the solution extraction system comprises a first solution extraction circuit and a second solution extraction circuit. A first metal-bearing solution is provided to the first and second circuit, and a second metal-bearing solution is provided to the first circuit. The first circuit produces a first rich electrolyte solution, which can be forwarded to primary metal value recovery, and a low-grade raffinate, which is forwarded to secondary metal value recovery. The second circuit produces a second rich electrolyte solution, which is also forwarded to primary metal value recovery. The first and second solution extraction circuits have independent organic phases and each circuit can operate independently of the other circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/837,158, entitled “SYSTEM AND METHOD FORPARALLEL SOLUTION EXTRACTION OF ONE OR MORE METAL VALUES FROMMETAL-BEARING MATERIALS,” which was filed on Mar. 15, 2013. The '158Application is a divisional application of and claims priority to U.S.patent application Ser. No. 13/331,699, entitled “SYSTEM AND METHOD FORPARALLEL SOLUTION EXTRACTION OF ONE OR MORE METAL VALUES FROMMETAL-BEARING MATERIALS,” which was filed on Dec. 20, 2011, now U.S.Pat. No. 8,420,048 issued Apr. 16, 2013. The aforementioned applicationsare hereby incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present invention relates generally to processes and systems forrecovery of one or more metals from metal-bearing materials. Moreparticularly, the invention relates to metal recovery systems whichinclude solution extraction and to methods of using the systems.

BACKGROUND OF THE INVENTION

Hydrometallurgical treatment of metal-bearing materials, such as metalores, metal-bearing concentrates, and other metal-bearing substances,has been well established for many years. Moreover, leaching ofmetal-bearing materials is a fundamental process utilized to extractmetals from metal-bearing materials. In general, the first step in thisprocess is contacting the metal-bearing material with an aqueoussolution containing a leaching agent or agents which extract the metalor metals from the metal-bearing material into solution to yield anaqueous metal-bearing pregnant leach solution. For example, in copperleaching operations, especially operations involving copper recoveryfrom copper-containing minerals such as chalcopyrite, chalcocite,covellite, malachite, pseudomalachite, azurite, chrysocolla, andcuprite, sulfuric acid in an aqueous solution is contacted withcopper-bearing ore. During the leaching process, acid in the leachsolution may be consumed and various soluble metal components aredissolved, thereby increasing the metal content of the aqueous solution.

The aqueous leach solution containing the leached metal can then betreated via a process referred to as solution extraction (also referredto as solvent or liquid-liquid extraction or liquid ion exchange)wherein the aqueous leach solution is contacted with an organic solutioncomprising a metal extraction reagent, for example, an aldoxime and/orketoxime or a mixture thereof. The metal extraction reagent extracts themetal from the aqueous phase into the organic phase. Moreover, duringthe solution extraction process for copper and certain other metals,leaching agent may be regenerated in the aqueous phase. For example, inthe case where sulfuric acid is the leaching agent, sulfuric acid isregenerated in the aqueous phase when copper is extracted into theorganic phase by the extraction reagent.

In a typical agitation leaching process for copper, followed by solutionextraction, the leach solution may be diluted to a lesser or greaterextent with acidified water in conjunction with the solid-liquidseparation process needed to provide a clarified leach liquor and soliddischarge. The diluted clarified leach solution then typically undergoessolution extraction at a solution-extraction plant or facility, whereina primary metal value, for example, copper, is removed from, and thesulfuric acid concentration is increased in, the aqueous phase. Aportion of this copper-depleted, acid-containing aqueous phase, nowcalled the raffinate, may be recycled back to the leaching process,recycled to the front of the solid-liquid separation process, and/orforwarded to secondary metal extraction processes, including but notlimited to cobalt recovery. Alternatively, leach streams of differentgrades may be treated at separate plants or facilities and therespective raffinates and organic solutions may be cycled or recycledwithin such plants or facilities.

Using typical leaching and solution extraction processes, largeconcentrations of soluble metal and metal precipitate of a primary metalvalue can be lost in the metal-depleted, acid-containing raffinate.These losses lead to inefficiencies and low overall process yields.Furthermore, these high metal concentrations in the raffinate may makerecovery of secondary metals relatively costly and possibly impractical.

Typically, a solution-extraction plant includes a single circuit toextract the metal values from the leach solution. Although this can workrelatively well in some circumstances, recovery of a primary metal valuefrom leach solutions using a single-circuit solution-extraction plant orfacility can lead to significant down-time and decreased metal output ofthe primary metal value when the solution extraction circuit isinoperative due to, for example, necessary repairs or maintenance.

Accordingly, a process and system that use solution extraction toextract a primary metal value from a leach solution and decrease theconcentration of the primary metal value, for example, copper, in theresultant raffinate solution, while simultaneously providing forincreased loading of the primary metal value in the metal extractionreagent, are desirable. In addition, an improved process and system thatreduce plant down-time are desired.

SUMMARY OF THE INVENTION

The present invention relates generally to a system and process forrecovery of one or more metal values from metal-bearing materials. Invarious aspects of exemplary embodiments, recovery of metal values froma metal-bearing material is improved by providing a solution extractionsystem and process that include at least two metal-bearing solutions andat least two solution extraction circuits. As set forth in more detailbelow, various advantages of the system and method of the presentinvention include robust primary metal value recovery, improvedsecondary metal value recovery, and/or improved solution extractionfacility utilization.

In accordance with various embodiments, a system for solution extractionof one or more metal values comprises a first metal-bearing solution, asecond metal-bearing solution, a first solution extraction circuit, anda second solution extraction circuit. In accordance with various aspectsof these embodiments, the first solution extraction circuit is coupledto the first metal-bearing solution and the second metal-bearingsolution and comprises at least two extractors and at least onestripping unit. In accordance with further aspects, the second solutionextraction circuit is coupled to the first metal-bearing solution andcomprises at least one extractor and at least one stripping unit. Inaccordance with additional aspects, the first solution extractioncircuit includes four extractors and two stripping units, and the secondsolution extraction circuit includes two extractors and one strippingunit.

In accordance with additional exemplary embodiments, a solutionextraction process comprises providing a first metal-bearing solution toa first solution extraction circuit and a second solution extractioncircuit, and providing a second metal-bearing solution to the firstsolution extraction circuit. In accordance with various aspects of theseexemplary embodiments, the first solution extraction circuit produces afirst rich electrolyte solution and a low-grade raffinate, and thesecond solution extraction circuit produces a second rich electrolytesolution. In accordance with additional aspects, the first solutionextraction circuit produces a first high-grade raffinate and the secondsolution extraction circuit produces a second high-grade raffinate. Inaccordance with yet further aspects, the first metal-bearing solution isprovided to a first extractor of the first circuit and a first extractorof the second circuit. And, in accordance with yet further aspects, thesecond metal-bearing solution is provided to a third extractor of thefirst circuit.

In accordance with yet further aspects of the embodiments, a metalrecovery process comprises preparing a metal-bearing material,performing a reactive process on the metal-bearing material, subjectingthe metal-bearing material to a conditioning step, subjecting themetal-bearing material to a solution extraction step using the solutionextraction system and process described herein, and subjecting theresultant rich electrolyte solutions and low-grade raffinate to metalvalue recovery.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present invention, however, may bestbe obtained by referring to the detailed description when considered inconnection with the drawing figures, wherein like numerals denote likeelements and wherein:

FIG. 1 illustrates a flow diagram of a metal recovery process inaccordance with exemplary embodiments of the present invention;

FIG. 2 illustrates a flow diagram of a solution extraction process forrecovery of one or more metal values in accordance with exemplaryembodiments of the present invention; and

FIG. 3 illustrates a solution extraction system for processing multiplemetal-bearing solution streams using two solution extraction circuits inaccordance with exemplary embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The detailed description of exemplary embodiments of the inventionherein sets forth various exemplary embodiments. While these exemplaryembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, it should be understood that otherembodiments may be realized and that logical and mechanical changes maybe made without departing from the spirit and scope of the presentinvention. Rather, the following disclosure is intended to teach boththe implementation of the exemplary embodiments and any equivalentembodiments. Additionally, all included figures are non-limitingillustrations of the exemplary embodiments and modes, which similarlyavail themselves of any equivalent embodiments.

As set forth in more detail below, various embodiments of the presentinvention provide significant advancements over prior art processes,particularly with regard to metal recovery and process efficiency.Moreover, existing copper recovery processes that utilize a reactiveprocess for metal recovery that also involves solution extraction andelectrowinning processes may, in many instances, be easily retrofittedto exploit the many commercial benefits the present invention provides.

In various exemplary embodiments, a metal recovery process comprisespreparing a metal-bearing material, performing a reactive process on themetal-bearing material, extracting metal value from the processedmetal-bearing material, and subjecting the extracted metal value to atleast one metal recovery step, such as electrowinning.

FIG. 1 illustrates an exemplary metal recovery process 100 forrecovering a metal from a metal-bearing material 101, including thesteps of preparing metal-bearing material step 10, reactive processingstep 20, optional conditioning step 30, solution extraction step 40,primary metal recovery step 50 and optional secondary metal recoverystep 60. In various exemplary embodiments, metal recovery process 100 isconfigured to recover multiple metal values from metal-bearing material101. For example, metal recovery process 100 may be configured torecover a primary and a secondary metal, such as cobalt, from an oreand/or concentrate comprising a significant concentration of the primarymetal.

Metal-bearing material 101 may be an ore, a concentrate, or any othermaterial from which valuable and/or useful metal values may berecovered. Such metal values may include, for example, copper, gold,silver, zinc, platinum group metals, nickel, cobalt, molybdenum,rhenium, uranium, rare earth metals, and the like. By way of a specificexample, metal recovery process 100 is configured to recover copper fromcopper-bearing material, such as, for example, ores and/or concentratescontaining chalcopyrite (CuFeS₂), chalcocite (Cu₂S), bornite (Cu₅FeS₄),and covellite (CuS), malachite (Cu₂CO₃(OH)₂), pseudomalachite(Cu₅[(OH)₂PO₄]₂), azurite (Cu₃(CO₃)₂(OH)₂), chrysocolla((Cu,Al)₂H₂Si₂O₅(OH)₄.nH₂O), cuprite (Cu₂O), brochantite(CuSO₄.3Cu(OH)₂), atacamite (Cu₂[OH₃Cl]) and other copper-bearingminerals or materials and mixtures thereof.

During preparation of metal-bearing material step 10, metal-bearingmaterial 101 is prepared for reactive processing step 20. Metal-bearingmaterial 101 may be prepared in any manner that facilitates the recoveryof metal values from metal-bearing material 101—such as, for example,manipulating a composition and/or component concentration ofmetal-bearing material 101—for the chosen reactive processing method ofstep 20. Desired composition and component concentration parameters canbe achieved through a variety of chemical and/or physical processingstages, the choice of which will depend upon the operating parameters ofthe chosen processing scheme, equipment cost and materialspecifications. For example, metal-bearing material 101 may undergocomminution, flotation, blending, and/or slurry formation, as well aschemical and/or physical conditioning in preparation step 10 beforemetal extraction. Any processing of metal-bearing material 101 whichimproves the ability to recover metal values from the material is inwithin the scope of the present disclosure.

In various exemplary embodiments, step 10 comprises a controlledgrinding step. Controlled grinding may be used to produce a uniformparticle size distribution of metal-bearing material 101. Additionally,liquid, such as process water, may be added to metal-bearing material101 to create a pulp density which corresponds to desirable operatingconditions of the controlled grinding unit. Acceptable techniques anddevices for reducing the particle size of the metal-bearing materialinclude, for example, ball mills, tower mills, grinding mills, attritionmills, stirred mills, horizontal mills and the like, and additionaltechniques may later be developed and achieve the desired result ofreducing the particle size of the metal-bearing material.

After metal-bearing material 101 has been suitably prepared for metalrecovery processing, it may be combined with any number of liquid feedstreams to form a metal-bearing inlet stream 103. Preferably, in anexemplary embodiment of the present invention, the liquid feed streamcomprises process water, but any suitable liquid may be employed, suchas, for example, recycled raffinate, pregnant leach solution, leanelectrolyte, and/or other recycled streams from the metal recoveryprocesses, including but not limited to secondary metal, such as cobaltor iron, recovery process streams.

After step 10, metal-bearing inlet stream 103 may be forwarded to areactive processing step 20. Step 20 may comprise any process orreaction which places metal-bearing inlet stream 103 in condition forlater metal recovery processing. Such processes may include, forexample, a leaching step. In such configurations, the leaching step maycomprise atmospheric leaching, ammonia leaching, pressure leaching,whole ore leaching, agitation leaching, heap leaching, stockpileleaching, pad leaching, thin-layer leaching, and/or vat leaching, ateither ambient or elevated temperatures, or any process or reaction thatputs metal values in metal-bearing inlet stream 103 in a conditionsuitable for later metal recovery processing, is within the scope of thepresent disclosure.

During step 20, metal values are solubilized or otherwise liberated fromthe metal-bearing material in preparation for later recovery processes.Any substance that assists in solubilizing metal values, and thusreleasing metal values from a metal-bearing material, may be used. Forexample, where copper is the metal being recovered, an acid, such assulfuric acid, may be contacted with the copper-bearing material suchthat the copper is solubilized for later recovery steps. However, itshould be appreciated that any suitable method of solubilizing metalvalues in preparation for later metal recovery steps is within the scopeof the disclosure.

After step 20, the metal-bearing product stream 105 may undergo one ormore optional conditioning steps 30. In an exemplary embodiment, productstream 105 of reactive processing step 20 is conditioned to adjust thecomposition, component concentrations, solids content, volume,temperature, pressure, and/or other physical and/or chemical parametersto desired values. Generally, a properly conditioned metal-bearingproduct stream 105 will contain a relatively high concentration ofsoluble metal, for example, copper sulfate, in an acid solution and maycontain few impurities. Moreover, the conditions of the metal-bearingproduct stream 105 may be kept substantially constant to enhance thequality and uniformity of the copper product ultimately recovered.

By way of example, step 30 may comprise adjusting certain physicalparameters of the metal-bearing product stream 105. Step 30 maycomprise, for example, reagent additions, flashing processes, and one ormore solid-liquid phase separation steps. For example, in variousexemplary embodiments, product stream 105 may be further conditioned inpreparation for later metal value recovery steps by one or moresolid-liquid phase separation steps for the purpose of separatingsolubilized metal solution from solid particles. This may beaccomplished in any conventional manner, including use of filtrationsystems, CCD circuits, thickeners, clarifiers, and the like. A varietyof factors, such as, for example, the process material balance,environmental regulations, residue composition, economic considerations,may affect the decision of which type of solid-liquid phase separationstep to employ. In accordance with the various embodiments, one or moresolid-liquid phase separation steps may be carried out using aconventional CCD circuit for washing of the residue stream to recoverleached metal values to one or more solution products and to minimizethe amount of soluble metal values advancing with the solid residue tofurther metal recovery processes or storage.

In various exemplary embodiments, step 30 comprises a solid-liquid phaseseparation step to produce a first metal-bearing solution and a secondmetal-bearing solution. In such embodiments, the first metal-bearingsolution comprises a high-grade pregnant leach solution (“HGPLS”) 102,comprising a relatively high concentration of dissolved primary metalvalue, and the second metal-bearing solution comprises a low-gradepregnant leach solution (“LGPLS”) 106, comprising a lower concentrationof dissolved primary metal value than HGPLS 102. While the concentrationof a primary metal value in both HGPLS and LGPLS may vary on an absolutebasis, in various embodiments, the HGPLS will have a higherconcentration of a primary metal value than the LGPLS. Stated anotherway, HGPLS and LGPLS may contain very low, or very high, primary metalvalue concentrations.

In various exemplary embodiments, large amounts of wash water areutilized in a solid-liquid phase separation in step 30. This wash watercollects the remaining dissolved metal values from product stream 105and may become part of LGPLS 106. The separated solids may further besubjected to later processing steps, including other metal recoveryprocesses, such as, for example, recovery of gold, silver, platinumgroup metals, molybdenum, zinc, nickel, cobalt, uranium, rhenium, rareearth metals, and the like, by sulphidation, cyanidation, or othertechniques. Alternatively, the separated solids may be subject toimpoundment or disposal.

In various exemplary embodiments, at least one HGPLS (e.g., HGPLS 102)and at least one LGPLS (e.g., LGPLS 106) are forwarded to solutionextraction step 40. Step 40 produces at least one primary metal valuecontaining rich electrolyte solution 192 and may produce one or moresecondary metal value containing streams, e.g., low-grade raffinate 146.For example, as discussed in connection with FIG. 2 and FIG. 3, twoHGPLS streams and one LGPLS stream may be forwarded to solutionextraction step 40. In other aspects, a single HGPLS stream and a singleLGPLS stream may be provided to solution extraction step 40, and theHGPLS stream may be divided into multiple streams during step 40.

In many instances, due to variations in concentration and quality of themetal-bearing material 101, it may be advantageous to mix one or moreleach solutions prior to solution extraction to form a firstmetal-bearing solution and/or a second metal-bearing solution.Additionally or alternatively, it may be beneficial to process two ormore separate leach solution streams produced by multiple leachprocesses in a single solution extraction process or system. Forexample, if an operation has both a heap leach operation and a pressureor agitated leach operation, then the heap leach solution, equivalent tothe LGPLS, may need to be processed with a more concentrated pregnantleach solution, such as HGPLS, in order to provide for efficient use ofthe metal extraction reagent in the organic solution and the solutionextraction system. It is not required that the HGPLS and LGPLS areproduced from the same metal recovery process steps. In accordance withan exemplary embodiment of the present invention, either HGPLS 102,LGPLS 106, or both can be produced from one or more metal-bearingmaterials 101, and/or by one or more preparation, reactive processing,and/or conditioning steps (steps 10, 20, 30) and be subjected tosolution extraction in the same solution extraction system.

In various exemplary embodiments, the LGPLS has a concentration of aprimary metal value greater than about 20% of the concentration of theprimary metal value in the HGPLS. Preferably, the LGPLS has aconcentration of the primary metal value greater than about 40% of theconcentration of the primary metal value in the HGPLS. Most preferably,the LGPLS has a concentration of the primary metal value greater thanabout 50% of the concentration of the primary metal value in the HGPLS.However, the use of the terms HGPLS and LGPLS should not be construed aslimiting the present disclosure, and any relationship of the primarymetal value concentrations between the metal-bearing solutions is withinthe scope of the present invention.

In step 40, at least one raffinate may be produced. The at least oneraffinate can be low-grade raffinate 146, comprising a relatively lowprimary metal value concentration and a relatively high secondary metalvalue concentration. The low-grade raffinate may be forwarded tosecondary metal value recovery processes, such as a secondary metalvalue recovery step 60, as discussed in more detail below.

Solution extraction step 40 of FIG. 1 is described in greater detailbelow with reference to a solution extraction process 200, illustratedin FIG. 2, and to a solution extraction system 300, illustrated in FIG.3.

Generally, and as illustrated in FIG. 2, solution extraction process 200comprises providing a first metal-bearing solution to a first solutionextraction circuit and a second solution extraction circuit (step 297),providing a second metal-bearing solution to the first solutionextraction circuit (step 298), producing a first rich electrolytesolution from the first solution extraction circuit (step 230),producing a low-grade raffinate from the first solution extractioncircuit (step 221), and producing a second rich electrolyte solutionfrom the second solution extraction circuit (step 270).

In accordance with exemplary embodiments, providing a firstmetal-bearing solution to a first and second solution extraction circuitstep 297 comprises providing HGPLS 102, and providing a secondmetal-bearing solution to a first solution extraction circuit step 298comprises providing LGPLS 106. In accordance with the various exemplaryembodiments, HGPLS 102 is divided into at least two HGPLS streams thatmay be forwarded to at least two independent solution extractioncircuits for solution extraction of a primary metal value. In accordancewith exemplary embodiments of the present invention, HGPLS 102 from asingle source, such as, for example, a HGPLS pond, is divided into afirst HGPLS stream 208 and a second HGPLS stream 209. In accordance withother embodiments, first HGPLS stream 208 and second HGPLS stream 209may be produced from distinct metal-bearing materials, preparations ofmetal-bearing material, reactive processing steps, conditioning steps,or any combination thereof. It should be understood that the source,identity, similarity, or composition of the first HGPLS stream 208 andsecond HGPLS stream 209 is not to be construed as a limitation to thescope of the present disclosure and that although HGPLS streams 208 and209 are illustrated as originating from the same source, they need notdo so; HGPLS streams 208 and 209 that are either substantially the sameor substantially different are within the scope of the presentinvention.

In accordance with the illustrated embodiments, first HGPLS stream 208is forwarded to a first solution extraction circuit 219, and secondHGPLS stream 209 is forwarded to a second solution extraction circuit259, the organic phase of which is separate from the organic phase offirst solution extraction circuit 219 and which may be operatedindependently of the operational state of first solution extractioncircuit 219. Furthermore, in accordance with exemplary embodiments,LGPLS 106 is also forwarded to first solution extraction circuit 219 forsolution extraction of the primary metal value from LGPLS 106.

Generally, in accordance with exemplary embodiments and as will bedescribed in greater detail below, in first circuit 219, LGPLS 106 issubjected to solution extraction in step 221, wherein low-graderaffinate 146 is produced. In accordance with further aspects, firstHGPLS stream 208 is subjected to solution extraction in step 220,wherein a first high-grade raffinate 204 is produced. A first richelectrolyte solution 162, e.g., a solution containing a highconcentration of the primary metal value, is produced in stripping step230.

Additionally, in accordance with exemplary embodiments, in secondcircuit 259, second HGPLS stream 209 is subjected to solution extractionin step 260, wherein a second high-grade raffinate 207 is produced. Inaccordance with further aspects, stripping step 270 produces a secondrich electrolyte solution 192, preferably containing a highconcentration of the primary metal value.

As illustrated in FIG. 3, solution extraction system 300 forimplementing the solution extraction process 200 comprises firstmetal-bearing solution (HGPLS 102), second metal-bearing solution (LGPLS106), first solution extraction circuit 219 coupled to firstmetal-bearing solution 102 and second metal-bearing solution 106, andsecond solution extraction circuit 259 coupled to first metal-bearingsolution 102. Further, in accordance with various aspects, and as willbe discussed in greater detail below, first solution extraction circuitcomprises 219 at least two extractors and at least one stripping unit,and second solution extraction circuit 259 comprises at least oneextractor and at least one stripping unit. In the illustrated example,first circuit 219 includes first and second high-grade extractors 322and 324, first and second low-grade extractors 323 and 325, and firstand second stripping units 332 and 334; second circuit 259 includesfirst and second high-grade extractors 362 and 364, and stripping unit372.

In the illustrated embodiments, first HGPLS stream 208 is coupled tofirst high-grade extractor 322 and LGPLS 106 is coupled to firstlow-grade extractor 323 in first circuit 219, while second HGPLS stream209 is coupled to first high-grade extractor 362 in second circuit 259.It should be understood, however, that LGPLS 106 may be forwarded tosecond circuit 259 in addition to or instead of first circuit 219. Itshould further be understood that solution extraction of the primarymetal value may be performed using two, three, four, or more independentsolution extraction circuits each separately used to perform solutionextraction of a HGPLS stream, and that at least one LGPLS 106 may beforwarded to any one or more of the independent solution extractioncircuits also used to perform solution extraction of a HGPLS stream,without departing from the scope of the present invention.

In accordance with the various exemplary embodiments, in first circuit219, first high-grade extractor 322, first low-grade extractor 323, andfirst stripping unit 332 are coupled to one another in a seriesconfiguration with respect to the common organic solution containing ametal extraction reagent, with first HGPLS stream 208 and LGPLS stream106 each subjected to solution extraction (steps 220 and 221,respectively, of FIG. 2) in at least a single extractor, and with aloaded organic solution 310 produced in first high-grade extractor 322forwarded to at least a single stripping unit, for example, strippingunit 334. Likewise, in second circuit 259, first high-grade extractor362 and first stripping unit 372 are also connected in a seriesconfiguration, with second HGPLS stream 209 subjected to solutionextraction (step 260 of FIG. 2) in at least a single extractor andloaded organic solution 350 forwarded to at least a single strippingunit. However, a system comprising the solution extraction circuitscoupled to the PLS sources described above and having any suitablenumber of extractors for each PLS stream coupled to a solutionextraction circuit and any suitable number of stripping units is withinthe scope of the present invention.

In first circuit 219, one or more additional high-grade extractors,illustrated as second high-grade extractor 324, may be coupled in aseries configuration between first high-grade extractor 322 and firstlow-grade extractor 323, and one or more additional low-gradeextractors, illustrated as second low-grade extractor 325, may becoupled in a series configuration between first low-grade extractor 323and first stripping unit 332. One or more additional stripping units,illustrated as second stripping unit 334, may be coupled in a seriesconfiguration between first high-grade extractor 322 and first strippingunit 332.

Likewise, in second circuit 259, one or more additional high-gradeextractors, illustrated as second high-grade extractor 364, may becoupled in a series configuration between first high-grade extractor 362and first stripping unit 372. One or more additional stripping units maybe coupled in a series configuration between first high-grade extractor322 and first stripping unit 332.

In the illustrated embodiment, in first circuit 219, second low-gradeextractor 325 receives metal-depleted organic solution 311 from firststripping unit 332 and intermediate low-grade raffinate 399 from firstlow-grade extractor 323, producing a first partially metal-loadedorganic solution 312 and low-grade raffinate 146. First low-gradeextractor 323 receives first partially metal-loaded organic solution 312and LGPLS 106, producing a second partially metal-loaded organicsolution 314 and intermediate low-grade raffinate 399. Second high-gradeextractor 324 receives second partially metal-loaded organic solution314 and an intermediate high-grade raffinate 303, producing a thirdpartially metal-loaded organic solution 316 and a high-grade raffinate204. First high-grade extractor 322 receives third metal-loaded organicsolution 316 and first HGPLS stream 208, producing loaded organicsolution 310 and intermediate high-grade raffinate 303. Second strippingunit 334 receives loaded organic solution 310 and a partiallymetal-loaded electrolyte solution 344, producing rich electrolytesolution 162 and a partially metal-depleted organic solution 313. Firststripping unit 332 receives partially metal-depleted organic solution313 and lean electrolyte solution 340, producing metal-depleted organicsolution 311 and partially metal-loaded electrolyte solution 344.

In second circuit 259 of solution extraction system 300, secondhigh-grade extractor 364 receives metal-depleted organic solution 351from first stripping unit 372 and an intermediate high-grade raffinate306 from first high-grade extractor 362, producing a partiallymetal-loaded organic solution 353 and a second high-grade raffinate 207.First high-grade extractor 362 receives partially metal-loaded organicsolution 353 and second HGPLS stream 209, producing a metal-loadedorganic solution 350 and intermediate high-grade raffinate 306. Firststripping unit 372 receives loaded organic solution 350 and a secondlean electrolyte solution 380, producing metal-depleted organic solution351 and second rich electrolyte solution 192.

The particular embodiment described in connection with FIG. 3 merelyillustrates an exemplary system for solution extraction in accordancewith the present disclosure. Various other exemplary embodimentscomprise multiple stripping units and extractors arranged in series,parallel, and/or split configurations. For example, various exemplaryembodiments may utilize a first circuit and/or second circuit withadditional or fewer stripping units and/or extractors than first circuit219 and/or second circuit 259. The use of any suitable number ofstripping units and extractors, in any suitable configuration, is withinthe scope of the present disclosure.

High-grade raffinates 204 and 207 may be used beneficially in a numberof ways. For example, all or portions of high-grade raffinates 204 and207 maybe recycled to reactive processing step 20 (FIG. 1). The use ofhigh-grade raffinates 204 and 207 in heap leaching operations may bebeneficial because the acid and ferric iron values contained inhigh-grade raffinates 204 and 207 may optimize the potential forleaching oxide and/or sulfide ores that commonly dominate many leachingoperations. For example, the ferric and acid concentrations ofraffinates 204 and 207 may be used to optimize the Eh and pH of heapleaching operations. It should be appreciated that the properties ofhigh-grade raffinates 204 and 207, such as component concentrations, maybe adjusted in accordance with their desired uses. It should further beunderstood that all or portions of high-grade raffinates 204 and 207 maybe combined in a high-grade raffinate storage unit prior to thesubsequent uses described above, or that all or portions of high-graderaffinates 204 and 207 may be maintained separately without departingfrom the scope of the present invention.

It is desirable to produce metal-loaded organic solutions 310 and 350with high primary metal value concentrations, which are suitablyconditioned for metal recovery by stripping and electrowinning inprimary metal value recovery 50 (FIG. 1). Additionally, in the firstsolution extraction circuit 219 coupled to LGPLS 106, it is desirable toproduce a low-grade raffinate 146, which contains a very low primarymetal value concentration and is suitable for secondary metal valuerecovery 60 (FIG. 1). In order to accomplish this, and in accordancewith exemplary embodiments of the present invention, the metal-depletedorganic solution 311 flow rate may be varied in correlation to theconcentration of primary metal value in the incoming metal-bearingmaterial and may be produced in one or more stripping units illustratedas first stripping unit 332 and second stripping unit 334. Additionally,in accordance with exemplary embodiments of the present invention, anysuitable metal extraction reagent may be supplied to the organicsolution in a solution extraction circuit by an external feed to thestripping units or to any other point prior to the organic solutioncontacting LGPLS 106. In accordance with exemplary embodiments of thepresent invention, the concentration of the metal extraction reagent inthe metal-depleted organic solution 311 may also be varied incorrelation to the grade of the incoming metal-bearing material.

As mentioned above, in accordance with exemplary embodiments of thepresent invention and referring to FIG. 2 and FIG. 3, metal-loadedorganic solutions 310 and 350 are introduced to stripping units 334 and372, and at least one metal value is stripped from each in strippingsteps 230 and 270, respectively, wherein rich electrolyte solutions 162and 192 are produced. In accordance with exemplary embodiments of thepresent invention, stripping steps 230 and 270 are performed using anyfluid suitable for stripping metal values from a metal-loaded organicsolution, such as lean electrolyte solutions 340 and 380 recycled fromone or more electrowinning circuits in a primary metal value recoveryprocess 50 (FIG. 1), described in detail below.

In accordance with various embodiments of the present invention and withreference now to FIG. 1 and FIG. 3, the primary metal value is removedfrom rich electrolyte solutions 162 and 192 during a primary metal valuerecovery process 50 such as, for example, electrowinning to yield apure, cathode metal product. However, step 50 may comprise any metalrecovery process, for example, electrowinning, sulphidation,precipitation, ion exchange or any other process suitable for recoveryof metals, and may produce a pure metal product. In accordance with thevarious embodiments of the present invention, step 50 produces a primarymetal value product and lean electrolyte solutions 340 and 380. Asmentioned above, lean electrolyte solutions 340 and 380 can be recycledto solution extraction system 300, a lean electrolyte solution storageunit, and/or reactive processing step 20. In accordance with anexemplary embodiment of the present invention, rich electrolytesolutions 162 and 192 are forwarded to a rich electrolyte solutionstorage unit for processing in primary metal value recovery process 50.However, it should be understood that rich electrolyte solutions 162 and192 may be forwarded to separate primary metal value recovery processes,that lean electrolyte solutions 340 and 380 may originate from distinctsources or primary metal value recovery processes, and that the leanelectrolyte solution sources are not limited by the exemplary embodimentdescribed above.

Referring now to FIG. 1 and FIG. 2, an exemplary secondary metalrecovery step 60 includes recovering metal from a low-grade raffinate.In various exemplary embodiments, step 60 may comprise any metalrecovery process such as, for example, electrowinning, sulphidation,precipitation, ion exchange, cyanidation, or any other process suitablefor recovery of secondary metals. Further, as discussed in some detailbelow, in various exemplary embodiments, precipitation processes areused, making it advantageous to have low concentrations of primarymetals in low-grade raffinate 146. Low-grade raffinate 146 may be sentto secondary metal value recovery 60 for extraction of secondary metalvalues including, but not limited to silver, platinum group metals,molybdenum, zinc, nickel, cobalt, uranium, rhenium, rare earth andactinide metals.

As mentioned above, the quality of metal-bearing material 101 can varywidely over the course of a metal recovery process 100. Due to thisvariation, both primary and secondary metal recovery processes canevidence losses in efficiency and overall processing yields. One reasonfor these losses is the inability to control and tune the quality andcomposition of low-grade raffinate 146 from solution extraction step 40.For example, low-grade raffinate 146 may be subjected to a selectiveprecipitation process wherein all metal ions except for those of thesecondary metal to be recovered such as, for example, cobalt, areeliminated from low-grade raffinate 146 by precipitating them as solids.These precipitated primary metal solids may be recycled to step 20.These precipitated solids may have a high probability of being renderedunrecoverable, depending on the precipitating mechanism employed. In theinstance where there is high primary metal concentration in low-graderaffinate 146, the amount of precipitated primary metal solids recycledto step 20 may increase. This increase in precipitated metal solids maylead to process inefficiencies due to high circulating loads in varioussteps 30 and 40.

Similarly, the inability to control and tune the quality andconcentration of low-grade raffinate 146 directly affects the costsassociated with step 60. For instance, low primary metal quality andconcentration in low-grade raffinate 146 requires less reagent to effectprecipitation (operating cost savings). Thus smaller equipment can beused to recycle the copper precipitate (capital cost savings).

Various embodiments of the present metal recovery process advantageouslyallow for control and tuning of the low-grade raffinate 146 in asolution extraction circuit. Moreover, solution extraction step 40 mayallow for control and tuning of low-grade raffinate 146 by adjustment ofparameters such as, for example, the metal-depleted organic solutionflow rate, metal extraction reagent concentration, feed material flowrate, and/or any combination thereof. Additionally, in various exemplaryembodiments, the overall efficiency of the metal recovery process may beinfluenced by blending the primary metal solids precipitated from thelow-grade raffinate with high-grade raffinate prior to recycling to thereactive process step. It should be understood that any of theseparameters may be advantageously adjusted or controlled as may bedesired to suitably adjust the concentration of primary metal value inthe low-grade raffinate entering secondary metal recovery processes.

By making any of these adjustments to control and tune the metal valueconcentration in the low-grade raffinate based on incoming metal orquality, the low-grade raffinate may desirably contain very limitedamounts of the primary metal value to promote efficient secondary metalvalue recovery, for example, recovery of cobalt. In an aspect of theseembodiments, because both the HGPLS and LGPLS streams are treated in onesolution extraction circuit, the primary metal value concentration ofthe LGPLS may be controlled and held constant by adjusting the LGPLSflow rate based on the primary metal value concentration. An additionalbenefit of the use of the exemplary process and system described herein,comprising two or more independent solution extraction circuits, is thatdown time due to maintenance or failure of an organic circuit component,such as an extractor or stripping unit, does not necessarily lead to acomplete shutdown of the metal value recovery process. Separation ofHGPLS into multiple streams for solution extraction processing usingmultiple, independent solution extraction circuits permits robust,ongoing recovery of a primary metal value despite a single solutionextraction circuit being inoperative due to a need for maintenance,repair, or for any other reason. Stated another way, metal valuerecovery for a first metal value is more robust due to the parallelprocessing of HGPLS in two separate solution extraction circuits.

The solution extraction system of the present invention allows thesolution extraction circuits used for recovery of primary and secondarymetal values to be tuned and optimized, both in terms of metallurgicalperformance and capital and operating costs. There is a trade offbetween achieving optimum metallurgical performance and minimizing thecapital costs of the operating facility. The decisions made regardingthis trade-off are based on the performance and cost of the metalextraction reagent employed as well as the chemistry of the pregnantleach solution streams to be treated. For example, the use of a metalextraction reagent that exhibits rapid extraction kinetics may minimizethe number of sequential extractors needed to achieve a satisfactorylevel of metal recovery. The presence of iron, manganese, or chloride inthe pregnant leach solution streams may require the use of a wash stageprior to stripping. The number and placement of stripping units may bedecided based on the stripping kinetics of the extraction reagent aswell as its maximum metal loading capacity. Accordingly, variousconfigurations are within the scope of the present invention.

It is believed that the disclosure set forth above encompasses at leastone distinct invention with independent utility. While the invention hasbeen disclosed in the exemplary forms, the specific embodiments thereofas disclosed and illustrated herein are not to be considered in alimiting sense as numerous variations are possible. The subject matterof the inventions includes all novel and non-obvious combinations andsub combinations of the various elements, features, functions and/orproperties disclosed herein and their equivalents.

The method and system described herein may be implemented to recovercopper and other metals in a controlled manner. Other advantages andfeatures of the present systems and methods may be appreciated from thedisclosure herein and the implementation of the method and system.

What is claimed is:
 1. A metal value recovery system comprising: aprimary metal value recovery system; a secondary metal value recoverysystem; and a solution extraction system comprising: a first solutionextraction circuit coupled to the primary metal value recovery systemand to the secondary metal value recovery system, and a second solutionextraction circuit coupled to the primary metal value recovery system.2. The system of claim 1, wherein the primary metal value recoverysystem comprises one of an electrowinning circuit, a sulphidationsystem, a precipitation system, and an ion exchange system.
 3. Thesystem of claim 2, wherein the primary metal value recovery systemcomprises an electrowinning circuit.
 4. The system of claim 1, whereinthe first solution extraction circuit and the second solution extractioncircuit are configured to produce a rich electrolyte.
 5. The system ofclaim 4, wherein the rich electrolyte is in fluid communication with theprimary metal value recovery system.
 6. The system of claim 4, whereinthe first solution extraction circuit is configured to produce ahigh-grade raffinate and a low-grade raffinate.
 7. The system of claim6, wherein the low-grade raffinate is in fluid communication with thesecondary metal value recovery system.
 8. The system of claim 7, whereinthe secondary metal value recovery system is configured to perform aselective precipitation process to produce a precipitated metal ion anda secondary electrolyte.
 9. The system of claim 8, wherein theprecipitated metal ion is uranium.
 10. The system of claim 8, whereinthe low-grade raffinate comprises a secondary metal value.
 11. Thesystem of claim 10, wherein the secondary metal value recovery systemfurther comprises a secondary electrowinning circuit configured toextract a secondary metal value from the secondary electrolyte.
 12. Thesystem of claim 11, wherein the secondary metal value is cobalt.
 13. Thesystem of claim 4, wherein the high-grade raffinate is recycled to areactive processing system.
 14. A system for extracting metal valuecomprising: a solution extraction system comprising a first circuit anda second circuit, wherein the first circuit is configured to receive afirst metal bearing solution and to produce a first rich electrolyte;wherein the second circuit is configured to receive the first metalbearing solution and to produce a second rich electrolyte; and whereinthe first circuit is configured to receive a second metal bearingsolution and to produce a low-grade raffinate; a primary electrowinningcircuit configured to extract a primary metal value from the first richelectrolyte and the second rich electrolyte; and a secondary metal valuerecovery system configured to extract a secondary metal value from thelow-grade raffinate.
 15. The system of claim 14, wherein the low-graderaffinate comprises a secondary metal value comprising at least one ofsilver, platinum group metals, molybdenum, zinc, nickel, cobalt,uranium, rhenium, rare earth and actinide metals.
 16. The system ofclaim 15, wherein the secondary metal value recovery system isconfigured to perform a selective precipitation process to precipitate ametal ion.
 17. The system of claim 16, wherein the metal ion comprisesuranium.
 18. The method of claim 17, wherein the secondary metal valuerecovery system comprises a secondary electrowinning circuit.
 19. Themethod of claim 18, wherein the secondary metal value comprises cobalt.20. The method of claim 19, wherein the second metal-bearing solution isa low-grade pregnant leach solution.